President Reagan said yesterday that the treaty to eliminate medium- and shorter-range nuclear missiles in Europe "is not yet complete" because of disagreements over verification, and he criticized Congress for recent limits on the Strategic Defense Initiative (SDI).

Speaking at the White House to activists who support the prospective missile treaty, Reagan said he would be meeting soon with Soviet leader Mikhail Gorbachev "unless some hitch develops." He said it would "be hasty to assume that we're at the point where we are ready to put pen to paper and sign the treaty."

"For one thing, in at least one important area, verification, the treaty is not yet complete," Reagan said. "Any treaty that I agree to must provide for effective verification, including on-site inspection of facilities before and during reduction, and short-notice inspection afterward.

"The verification regime that we have put forward in Geneva is the most stringent in the history of Soviet arms-control negotaitions," Reagan added, although he was not more specific about the verification disagreements.

Reagan's comments came as Secretary of State George P. Shultz is meeting with Soviet Foreign Minister Eduard Shevardnadze in Geneva to make final arrangements for the summit here Dec. 8-10 and signing of the intermediate-range nuclear forces (INF) treaty.

White House officials have expressed confidence that the document will be ready to sign despite last-minute problems.

Shultz said he would offer the Soviets on-site inspection rights at a U.S. missile facility as part of an effort to strike the final bargain on the treaty.

Asked later yesterday why he was hinting at a possible hitch involving the summit, Reagan said he was just "being cagey."

In his speech, the president criticized restrictions placed on the SDI in a long-overdue defense authorization bill.

The compromise legislation, which Reagan is expected to sign, essentially holds the president through the end of his term to status-quo observance of the 1972 Antiballistic Missile Treaty and the unratified SALT II treaty.

This means that the administration would be bound through the end of the next fiscal year to honor the restrictive or traditional interpretation of the treaty and would have to limit SDI tests to those previously outlined to Congress.

Reagan said the Soviet Union has mounted a similar missile-defense effort called "Red Shield" that "actually dwarfs our SDI."

"Yet there's been a strange tendency by some in Congress to discuss SDI as if its funding could be determined by purely domestic considerations unconnected to what the Soviets are doing," he said. This was a reference to the congressional decision to trim Reagan's $5.7 billion request for SDI research to $3.9 billion.

Reagan, planning a visit today to a Martin Marietta facility near Denver that is conducting SDI-related research, is launching a campaign to persuade Americans that the system is defensive rather than offensive.

The campaign is, in part, an effort to shape public opinion about the system as Reagan begins talks with the Soviets on reducing strategic nuclear arsenals.

Describing the space-based missile-defense shield as a "vital insurance policy" against Soviet cheating or a nuclear weapon developed by a "madman," Reagan insisted that the program is "not a bargaining chip" for strategic arms reductions.

However, the president has suggested recently that he would be flexible in the SDI deployment schedule if needed to help gain an agreement on reducing strategic arms.

"We will research it. We will develop it. And when it's ready, we'll deploy it," he said yesterday.